09 town and country with a 3.8 code p0135

Hello guys and gals i have a 2009 town n country van with a 3.8 and i keep getting a p0135, ihave no voltage on my control wire for sensor 1/1 or 1/2 ive checked them both. im assuming its going to need an ecm what i dont understand is should there be twelve volts there key on, all the time? or does it some how very it? ready to pull my hair out thanks in advance.

P0135: Oxygen sensor bank one, sensor one heater circuit.

Service information states that heater voltage is pulse width modulated via the ECM (brown & tan) with a chassis ground (black).
So you will likely only have pulsed voltage on the heater control wire (not full battery voltage as measured with a meter) when the engine is running.
It's relatively easy to disconnect the oxygen sensor connector, identify the heater circuit pins, and connect a lightbulb between the two wires as a substitute load.
You may need to clear the codes, then start the engine. Within a few moments, the bulb should begin to flash and grow brighter as heater command is increased. If that's the case, then the sensor is the issue.

Hey groundblind!

To answer your question, the O2 heaters in your Town and Country will only have 12V on the heater control circuit when the PCM is commanding the heaters on. This system uses a high side driver to switch 12V on the control wires, while the other side of the heater is grounded all the time. The PCM will pulse width modulate the 12V power as needed to get the sensors warmed up.

Interestingly, your P0135 does not spell out a heater circuit problem. :huh: I snipped this from service information:

Theory of OperationThe Powertrain Control Module (PCM) performs a continuous check of the O2 sensor heater circuit during operation. The heater circuit is momentarily disabled to allow a resistance measurement to be taken to infer heater temperature. The current delivery to the heater is duty cycled to maintain a specific target temperature. The error from the target temperature is continuously monitored to assess heater performance. 

1. When Monitored:With the engine running, O2 sensor heater duty cycle greater than 0%, and battery voltage greater than 11.0 volts.
2. Set Condition:The PCM detects no O2 sensor output when the heater is powered up. Two trip fault. Three good trips to turn off the MIL.

 

In other words, the PCM is inferring heater operation by the behavior of the O2 sensor signal. Keep in mind that there are also several other faults that relate directly to the upstream O2 heater circuit (P0030, P0031, P0032, P0053).

If I were you, I'd suggest monitoring the upstream O2 sensor signal with a scan tool during a cold start. If the sensor is heating up like it should, the signal should drop well below 3.5V and start toggling once closed loop is achieved. If you have a scan tool with the O2 Heater Test, you can use that to command the heater circuits on and observe the sensor signal without the engine running. Again, the signal should drop well below 3.5V within a minute or two.

Has the upstream oxygen sensor been replaced before?

Can I swear lol? Freaking awesome response Tyler. Not surprised.
Man, the forum looks like s--t. Working on it, unfortunately it is the last item on the list, but we will get to it. Thanks so much for your patience and for always holding this part of my fort down for me.

Just seeing your post now too, thank you so much Noah! Same thing I just said to Tyler applies to you.
And man is this always this slow when I hit submit?
I just posted the same thing 4 times, hit submit twice and the browser just spun. smh. I assume this is new since the joomla 4 changeover? (the mess everything has been in the past 2 days)

Indeed the submit function went haywire, double and triple posting never was that easy....and the colours look... well ya know

The number of posts per page is drastically reduced as well.

We are on this juergen! I'm so sorry

No need to feel sorry, I know you'll get it fixed.

Thank you's go out to your team and yourself for all the good things you're doing.

ScannerDanner wrote:

Can I swear lol?
 

Hey, they're your forums!   

I just posted the same thing 4 times, hit submit twice and the browser just spun. smh. I assume this is new since the joomla 4 changeover? (the mess everything has been in the past 2 days)

Yeah that's new, but I figured there'd be some things to work through with the changeover.